This paper investigates an amplify and forward (AF) relaying scheme compatible with a legacy wireless system in cellular environments. In the proposed scheme, terminals and relay stations use different frequency bands for signal transmission. The two frequency bands for terminals and for relay stations are used by individual frequency reuse factors in cellular environments. We study frequency planning and a relay station's location for high spectral efficiency. The numerical results show that the spectral efficiency of a relaying scheme is enhanced by deploying a relay station close to the base station (BS) and using frequency reuse factor 1 for a relay station to BS link.